295 lines
9.6 KiB
Python
295 lines
9.6 KiB
Python
"""Generate ast module from specification
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This script generates the ast module from a simple specification,
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which makes it easy to accommodate changes in the grammar. This
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approach would be quite reasonable if the grammar changed often.
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Instead, it is rather complex to generate the appropriate code. And
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the Node interface has changed more often than the grammar.
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"""
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import fileinput
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import re
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import sys
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from StringIO import StringIO
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SPEC = "ast.txt"
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COMMA = ", "
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def load_boilerplate(file):
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f = open(file)
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buf = f.read()
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f.close()
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i = buf.find('### ''PROLOGUE')
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j = buf.find('### ''EPILOGUE')
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pro = buf[i+12:j].strip()
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epi = buf[j+12:].strip()
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return pro, epi
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def strip_default(arg):
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"""Return the argname from an 'arg = default' string"""
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i = arg.find('=')
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if i == -1:
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return arg
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t = arg[:i].strip()
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return t
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P_NODE = 1
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P_OTHER = 2
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P_NESTED = 3
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P_NONE = 4
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class NodeInfo:
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"""Each instance describes a specific AST node"""
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def __init__(self, name, args):
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self.name = name
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self.args = args.strip()
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self.argnames = self.get_argnames()
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self.argprops = self.get_argprops()
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self.nargs = len(self.argnames)
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self.init = []
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def get_argnames(self):
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if '(' in self.args:
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i = self.args.find('(')
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j = self.args.rfind(')')
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args = self.args[i+1:j]
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else:
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args = self.args
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return [strip_default(arg.strip())
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for arg in args.split(',') if arg]
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def get_argprops(self):
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"""Each argument can have a property like '*' or '!'
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XXX This method modifies the argnames in place!
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"""
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d = {}
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hardest_arg = P_NODE
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for i in range(len(self.argnames)):
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arg = self.argnames[i]
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if arg.endswith('*'):
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arg = self.argnames[i] = arg[:-1]
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d[arg] = P_OTHER
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hardest_arg = max(hardest_arg, P_OTHER)
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elif arg.endswith('!'):
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arg = self.argnames[i] = arg[:-1]
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d[arg] = P_NESTED
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hardest_arg = max(hardest_arg, P_NESTED)
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elif arg.endswith('&'):
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arg = self.argnames[i] = arg[:-1]
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d[arg] = P_NONE
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hardest_arg = max(hardest_arg, P_NONE)
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else:
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d[arg] = P_NODE
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self.hardest_arg = hardest_arg
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if hardest_arg > P_NODE:
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self.args = self.args.replace('*', '')
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self.args = self.args.replace('!', '')
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self.args = self.args.replace('&', '')
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return d
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def gen_source(self):
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buf = StringIO()
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print >> buf, "class %s(Node):" % self.name
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self._gen_init(buf)
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print >> buf
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self._gen_getChildren(buf)
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print >> buf
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self._gen_getChildNodes(buf)
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print >> buf
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self._gen_repr(buf)
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buf.seek(0, 0)
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return buf.read()
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def _gen_init(self, buf):
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if self.args:
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argtuple = '(' in self.args
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args = self.args if not argtuple else ''.join(self.argnames)
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print >> buf, " def __init__(self, %s, lineno=None):" % args
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else:
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print >> buf, " def __init__(self, lineno=None):"
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if self.argnames:
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if argtuple:
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for idx, name in enumerate(self.argnames):
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print >> buf, " self.%s = %s[%s]" % (name, args, idx)
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else:
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for name in self.argnames:
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print >> buf, " self.%s = %s" % (name, name)
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print >> buf, " self.lineno = lineno"
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# Copy the lines in self.init, indented four spaces. The rstrip()
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# business is to get rid of the four spaces if line happens to be
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# empty, so that reindent.py is happy with the output.
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for line in self.init:
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print >> buf, (" " + line).rstrip()
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def _gen_getChildren(self, buf):
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print >> buf, " def getChildren(self):"
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if len(self.argnames) == 0:
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print >> buf, " return ()"
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else:
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if self.hardest_arg < P_NESTED:
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clist = COMMA.join(["self.%s" % c
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for c in self.argnames])
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if self.nargs == 1:
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print >> buf, " return %s," % clist
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else:
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print >> buf, " return %s" % clist
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else:
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if len(self.argnames) == 1:
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print >> buf, " return tuple(flatten(self.%s))" % self.argnames[0]
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else:
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print >> buf, " children = []"
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template = " children.%s(%sself.%s%s)"
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for name in self.argnames:
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if self.argprops[name] == P_NESTED:
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print >> buf, template % ("extend", "flatten(",
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name, ")")
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else:
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print >> buf, template % ("append", "", name, "")
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print >> buf, " return tuple(children)"
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def _gen_getChildNodes(self, buf):
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print >> buf, " def getChildNodes(self):"
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if len(self.argnames) == 0:
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print >> buf, " return ()"
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else:
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if self.hardest_arg < P_NESTED:
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clist = ["self.%s" % c
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for c in self.argnames
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if self.argprops[c] == P_NODE]
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if len(clist) == 0:
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print >> buf, " return ()"
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elif len(clist) == 1:
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print >> buf, " return %s," % clist[0]
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else:
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print >> buf, " return %s" % COMMA.join(clist)
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else:
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print >> buf, " nodelist = []"
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template = " nodelist.%s(%sself.%s%s)"
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for name in self.argnames:
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if self.argprops[name] == P_NONE:
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tmp = (" if self.%s is not None:\n"
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" nodelist.append(self.%s)")
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print >> buf, tmp % (name, name)
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elif self.argprops[name] == P_NESTED:
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print >> buf, template % ("extend", "flatten_nodes(",
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name, ")")
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elif self.argprops[name] == P_NODE:
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print >> buf, template % ("append", "", name, "")
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print >> buf, " return tuple(nodelist)"
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def _gen_repr(self, buf):
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print >> buf, " def __repr__(self):"
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if self.argnames:
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fmt = COMMA.join(["%s"] * self.nargs)
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if '(' in self.args:
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fmt = '(%s)' % fmt
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vals = ["repr(self.%s)" % name for name in self.argnames]
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vals = COMMA.join(vals)
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if self.nargs == 1:
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vals = vals + ","
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print >> buf, ' return "%s(%s)" %% (%s)' % \
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(self.name, fmt, vals)
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else:
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print >> buf, ' return "%s()"' % self.name
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rx_init = re.compile('init\((.*)\):')
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def parse_spec(file):
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classes = {}
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cur = None
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for line in fileinput.input(file):
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if line.strip().startswith('#'):
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continue
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mo = rx_init.search(line)
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if mo is None:
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if cur is None:
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# a normal entry
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try:
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name, args = line.split(':')
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except ValueError:
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continue
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classes[name] = NodeInfo(name, args)
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cur = None
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else:
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# some code for the __init__ method
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cur.init.append(line)
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else:
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# some extra code for a Node's __init__ method
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name = mo.group(1)
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cur = classes[name]
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return sorted(classes.values(), key=lambda n: n.name)
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def main():
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prologue, epilogue = load_boilerplate(sys.argv[-1])
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print prologue
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print
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classes = parse_spec(SPEC)
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for info in classes:
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print info.gen_source()
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print epilogue
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if __name__ == "__main__":
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main()
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sys.exit(0)
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### PROLOGUE
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"""Python abstract syntax node definitions
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This file is automatically generated by Tools/compiler/astgen.py
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"""
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from consts import CO_VARARGS, CO_VARKEYWORDS
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def flatten(seq):
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l = []
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for elt in seq:
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t = type(elt)
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if t is tuple or t is list:
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for elt2 in flatten(elt):
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l.append(elt2)
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else:
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l.append(elt)
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return l
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def flatten_nodes(seq):
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return [n for n in flatten(seq) if isinstance(n, Node)]
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nodes = {}
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class Node:
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"""Abstract base class for ast nodes."""
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def getChildren(self):
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pass # implemented by subclasses
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def __iter__(self):
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for n in self.getChildren():
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yield n
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def asList(self): # for backwards compatibility
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return self.getChildren()
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def getChildNodes(self):
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pass # implemented by subclasses
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class EmptyNode(Node):
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pass
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class Expression(Node):
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# Expression is an artificial node class to support "eval"
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nodes["expression"] = "Expression"
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def __init__(self, node):
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self.node = node
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def getChildren(self):
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return self.node,
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def getChildNodes(self):
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return self.node,
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def __repr__(self):
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return "Expression(%s)" % (repr(self.node))
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### EPILOGUE
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for name, obj in globals().items():
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if isinstance(obj, type) and issubclass(obj, Node):
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nodes[name.lower()] = obj
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